We will continue our study of genes needed for neuronal differentiation and function in the nematode Caenorhabditis elegans. Most of the research will center, as in the past, on the analysis of the development and activity of the six touch receptor neurons (TRNs). Previous research under this grant has identified genes needed for the generation, specification, maintenance and function of the TRNs. In particular in the last funding period we enlarged the collection of TRN-expressed genes 8-fold to approximately 200 genes, identified components that restrict TRN development to six cells, and identified the transduction complex that sense touch in these cells. This last complex is the first transduction complex to be identified in any eukaryotic mechanosensory neuron. We also developed several new methods that we will exploit in the upcoming funding period. In particular we will investigate how cell fate is determined and maintained and how the lipid bilayer and extracellular matrix affect mechanosensation. The specific aims of the proposal are: 1) to investigate the regulation of post-mitotic gene expression, particular examining how genes needed only early in development of neurons are turned off; 2) to investigate the basis of cell-type specification within the TRNs; 3) to characterize lipid- binding and modulating components of the MEC-4 channel complex and similar proteins; and 4) to investigate the role of the extracellular matrix (ECM) in touch sensitivity. A secondary consequence of the proposed experiments will be the discovery a wealth of genes needed for general development and function of the C. elegans nervous system.